Process for producing L-amino acids

Abstract

A microorganism, which has an ability to produce L-amino acid, especially L-phenylalanine, L-tryptophane, L-tyrosine, L-threonine, or L-isoleucine, in which a phosphoenolpyruvate-producing ability is enhanced, is cultivated in a medium so that the L-amino acid is produced and accumulated in the medium to collect the L-amino acid.

What is claimed is:  
     
       1. A method for producing L-amino acid comprising cultivating in a medium a recombinant microorganism having an enhanced L-amino acid-producing ability, producing and accumulating the L-amino acid in the medium, and collecting the L-amino acid, wherein said amino acid is L-threonine or L-isoleucine, and wherein the said recombinant microorganism transformed with a gene encoding phosphoenolpyruvate synthase and a threonine operon comprising a gene coding for aspartokinase desensitized for feedback inhibition by L-threonine. 
     
     
       2. The method according to claim  1 , wherein the L-amino acid is L-threonine. 
     
     
       3. The method according to claim  1 , wherein the L-amino acid is L-isoleucine and wherein the said recombinant microorganism containing an ilvGMEDA operon comprising a gene coding for threonine deaminase desensitized for feedback inhibition by L-isoleucine. 
     
     
       4. The method according to claim  1 , wherein the microorganism is a Escherichia bacterium. 
     
     
       5. The method according to claim  1 , wherein the microorganism is a coryneform bacterium. 
     
     
       6. The method according to claim  1  wherein the recombinant microorganism comprises multicopies of the said gene coding for phosphoenolpyruvate synthase.